After I wrote my initial response, I checked back to make sure I was right about the amount of road walking involved. The first 15 kilometers is on dirt paths or very tranquil rural lanes. About 9-10 kilometers before Sobrado, you will hit the AS-924. This is a real road, and it will come as something of a shock after having walked the long rural stretch. Fortunately, even though it is a real road, it is not heavily traveled. Roughly half of the remaining distance to Sobrado will be on this road. Overall, it’s still a lovely day.
And later on, after Sobrado, if you want to put off the link-up with the Frances, I would strongly recommend the new Camino route, which splits off to the right after Boimorto. The junction is now very well-marked. Very, very quiet, and it’s also 8-10 kilometers shorter than if you went via Arzua. The only thing is, I would not follow the new route all the way to Lavacolla because the last 1/3 of it (or more) is along the very busy N-634. Better to cut off the new route and hit the Frances near Brea. Here's precise directions from a post of several years ago.
https://www.caminodesantiago.me/com...o-frances-later-off-the-camino-del-norte.509/. If you miss the cut-off to Brea, there is a further one another 7 kilometers on, which hits the Frances outside of O Pedrouzo. This cut-off is obvious.